U.S. patent application number 11/899124 was filed with the patent office on 2007-12-27 for dental adhesive compositions and methods.
Invention is credited to Huaibing Liu, Junjie Sang, Xiuling Wang.
Application Number | 20070299157 11/899124 |
Document ID | / |
Family ID | 33452339 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070299157 |
Kind Code |
A1 |
Sang; Junjie ; et
al. |
December 27, 2007 |
Dental adhesive compositions and methods
Abstract
Two-part and one-part self-etching dental adhesives containing
polymerizable acidic monomers. Methods include one-coat application
without need for tooth etching.
Inventors: |
Sang; Junjie; (Newark,
DE) ; Liu; Huaibing; (Dover, DE) ; Wang;
Xiuling; (Newark, DE) |
Correspondence
Address: |
DENTSPLY INTERNATIONAL INC
570 WEST COLLEGE AVENUE
YORK
PA
17404
US
|
Family ID: |
33452339 |
Appl. No.: |
11/899124 |
Filed: |
September 4, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10844628 |
May 13, 2004 |
|
|
|
11899124 |
Sep 4, 2007 |
|
|
|
60469938 |
May 13, 2003 |
|
|
|
Current U.S.
Class: |
523/118 |
Current CPC
Class: |
A61K 6/30 20200101; A61K
6/30 20200101; A61K 6/30 20200101; A61K 6/30 20200101; A61K 6/30
20200101; C08L 75/16 20130101; A61K 6/887 20200101; C08L 33/04
20130101; C08L 33/04 20130101; C08L 75/16 20130101 |
Class at
Publication: |
523/118 |
International
Class: |
C08K 3/00 20060101
C08K003/00 |
Claims
1. A dental adhesive comprising: (i) from about 5 to about 70% by
weight of polymerizable acids components selected from the group
consisting of PENTA, OEMA and mixtures thereof; (ii) from about 1
to about 30% by weight of hydrophilic methacrylate; (iii) from
about 1 to about 25% by weight of hydrophilic difunctional
(meth)acrylate; (iv) from about 1 to about 35% by weight of
Urethane methacrylate; (v) from about 1 to about 30% by weight of
hydrophobic difunctional (meth)acrylate; (vi) from about 0.1 to
about 5% photoinitiator of (phosphine oxide, and/or CQ/co-initiator
selected from the group consisting of Lucerin TPO, CQ/EDAB and
CQ/DMABN); (vii) from about 0.1 to about 5% curing additives
selected from the group consisting of aromatic sulfinate salts;
(viii) from about 0.1 to about 5% fluoride-releasing ingredient
selected from the group consisting of cetylamine hydrofluoride
(CAF); (ix) from about 0.1 to about 10% filler particles selected
from the group consisting of fumed silica and functionalized
nano-particles; (x) from about 0.05 to about 2% stabilize; (xi)
from about 1 to about 40% water; and (xii) from about 5 to about
60% water-miscible polar organic solvent selected from the group
consisting of acetone and alcohol.
2. A dental adhesive comprising: (i) from about 5 to about 50% by
weight of polymerizable acids components selected from the group
consisting of PENTA, 4-META and mixtures thereof; (ii) from about 1
to about 20% by weight of hydrophilic methacrylate; (iii) from
about 1 to about 15% by weight of hydrophilic difunctional
(meth)acrylate; (iv) from about 1 to about 30% by weight of
Urethane dimethacrylate; (v) from about 1 to about 30% by weight of
hydrophobic difunctional (meth)acrylate; (vi) from about 0.1 to
about 5% photoinitiators of (phosphine oxide, and/or
CQ/co-initiator selected from the group consisting of Lucerin TPO,
CQ/DMABN combination and L-TPO/CQ/EDAB combination); (vii) from
about 0.1 to about 5% curing additives selected from the group
consisting of aromatic sulfinate salts; (viii) from about 0.1 to
about 5% fluoride-releasing ingredient selected from the group
consisting of cetylamine hydrofluoride (CAF); (ix) from about 0.1
to about 10% filler particles selected from the group consisting of
fumed silica and functionalized nano-particles; (x) from about 0.05
to about 2% stabilize; (xi) from about 1 to about 35% water; and
(xii) from about 5 to about 60% water-miscible polar organic
solvent selected from the group consisting of acetone or alcohol.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/844,628 having a filing date of May 13,
2004 which claims the benefit of Provisional Application No.
60/469,938 filed on May 13, 2003.
TECHNICAL FIELD
[0002] The present invention generally relates to dental adhesives.
More particularly the invention relates to self-etching adhesives.
Specifically the invention relates to adhesives containing
polymerizable acidic monomers.
BACKGROUND OF THE INVENTION
[0003] Table of Abbreviations Used Herein TABLE-US-00001
Abbreviation Full term 4-META 4-methacryloxyethyltrimellitic
Anhydride AHPMA 3-(Acryloyloxy)2-hydroxypropyl methacrylate BHT
Butylated Hydroxytoluene BMAP Bis(2-methacryloxyethyl) phosphate
CAF Cetylamine Hydrofluoride CQ Camphorquinone DHEPT
Dihydroxylethyl-p-toluidine DMABA Dimethylaminobenzoic acid DMABN
Dimethylaminobenzonitrile EDAB 4-ethyldimethylaminbenzoate EGMP
Ethylene glycol methacrylate phosphate HEMA 2-Hydroxyethyl
methacrylate L-TPO Diphenyl (2,4,6-trimethylbenzoyl) phosphine
oxide NaTs Sodium salt of p-toluenesulfinic acid OEMA
4,4'-Oxydiphenylether 1,1',6,6'-tetracarboxylic acid-1,1'-(2-
methacryloxy) dimethacrylate PENTA Dipentaerythritol pentaacrylate
phosphoric acid ester PyroEMA Tetra-methacryloxyethyl Pyrophosphate
SBS Shear Bond Strength SCA Self-cure activator SEA Self-etching
adhesive 2P-SEA Two-Part Self-etching adhesive 1P-SEA One-Part
Self-etching adhesive VLC Visible Light Cure SC Self Cure (or
antocure) SUM summation TEGDMA Triethyleneglycoldimethacrylate
TMPTMA Trimethylolpropane Trimethacrylate UDMA
1,6-Bis[methacryloyloxyethoxycarbonylamino]-2,4,4-
tromethylhexane
[0004] As used herein all "%" and percents or the like are by
weight.
[0005] With the use of composite resins as dental restorative
materials, it is required to ensure firm adhesion between tooth
structures and composite resins by a simple handling. A
representative adhesive restoration procedure includes an acid
etching on tooth substrate by phosphoric acid, followed by water
rinsing, drying, application of a primer, drying, application of a
bonding agent, light-curing and finally filling of a composite
resin. It is apparent that it takes time in many bonding steps to
accomplish such handling and that no adhesion with confidence is
attained.
[0006] In order to reduce the number of constituents to be used,
priming and bonding were combined in one-bottle, so-called
one-bottle/two-step, exemplified by Prime & Bond.RTM. brand
adhesive (Dentsply). Etching must still be carried out first,
followed by the application of the single-bottle bonding at least
once and then polymerization, before the filling materials is used.
Another simplification of the process for the adhesive securing of
filling materials is to combine priming and etching into
one-component, so-called self-etching primers, such as SE Primer in
ClearFil SE Bond system [a 2-component (SE Primer and Bond liquid),
2-step, sequentially applied (SE Primer, followed by Bond resin)
self-etching adhesive by Kuraray]. ClearFil SE Bond is indicated
for direct light cured composite restoration bonding only. For
indirect restoration bonding, Kuraray recommends using ClearFil
Liner Bond 2V that is a multi-component (Primers A and B, Bond
Liquid A and B)/multi-steps application self etching adhesive
system.
[0007] Adper Prompt L-Pop (3M ESPE), so-called
2-component/one-pack/one-step self-etching and self-priming
adhesive, is supplied in a Single Unit Dose blister package that
consists of two-predosed compartments, or in two separate bottles
for the two liquids A and B. Prompt L-Pop is indicated for direct
light cured composite restoration bonding only.
[0008] Ref. U.S. Pat. No. 6,387,979 by K. Hino (Kuraray Co. Ltd.,
Japan), issued May 14, 2002 describes a tooth treated with a
bonding composition with high initial bonding strength and good
bonding durability comprising a mixture of polymerizable compound
having an acid group, a water-soluble film-forming agent, water,
and a curing agent, in which the calcium salt of the acid is
insoluble in water, and the film-forming agent is a polymerizable
compound miscible with a physiological saline solution, does not
require any pre-treatment such as acid-etching or priming
treatment. It is stated that the active ingredients of the
composition in a single package may degrade or polymerize while
stored. To prevent this, the constituent ingredients of the
composition may be divided into two or more parts. The plural parts
are separately packaged and stored in different packages. For their
use, the plural parts taken out of the individual packages may be
applied to one and the same object in sequence; or they may be
blended into one mixture just before use.
PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0009] In a preferred embodiment of the present invention, a dental
adhesive comprises: [0010] (i) from about 5 to 70% by weight of
polymerizable acids components selected from the group consisting
of PENTA, OEMA and mixtures thereof; [0011] (ii) from about 1 to
about 30% by weight of hydrophilic methacrylate; [0012] (iii) from
about 1 to about 25% by weight of hydrophilic difunctional
(meth)acrylate; [0013] (iv) from about 1 to about 35% by weight of
Urethane methacrylate; [0014] (v) from about 1 to about 30% by
weight of hydrophobic difunctional (meth)acrylate; [0015] (vi) from
about 0.1 to about 5% photoinitiator of (phosphine oxide, and/or
CQ/co-initiator selected from the group consisting of Lucerin TPO,
CQ/EDAB and CQ/DMABN); [0016] (vii) from about 0.1 to about 5%
curing additives selected from the group consisting of aromatic
sulfinate salts; [0017] (viii) from about 0.1 to about 5%
fluoride-releasing ingredient selected from the group consisting of
cetylamine hydrofluoride (CAF); [0018] (ix) from about 0.1 to about
10% filler particles selected from the group consisting of fumed
silica and functionalized nano-particles; [0019] (x) from about
0.05 to about 2% stabilize; [0020] (xi) from about 1 to about 40%
water; and [0021] (xii) from about 5 to about 60% water-miscible
polar organic solvent selected from the group consisting of acetone
and alcohol.
[0022] In another preferred embodiment, a dental adhesive
comprises: [0023] (i) from about 5 to about 50% by weight of
polymerizable acids components selected from the group consisting
of PENTA, 4-META and mixtures thereof; [0024] (ii) from about 1 to
about 20% by weight of hydrophilic methacrylate; [0025] (iii) from
about 1 to about 15% by weight of hydrophilic difunctional
(meth)acrylate; [0026] (iv) from about 1 to about 30% by weight of
Urethane dimethacrylate; [0027] (v) from about 1 to about 30% by
weight of hydrophobic difunctional (meth)acrylate; [0028] (vi) from
about 0.1 to about 5% photoinitiators of (phosphine oxide, and/or
CQ/co-initiator selected from the group consisting of Lucerin TPO,
CQ/DMABN combination and L-TPO/CQ/EDAB combination); [0029] (vii)
from about 0.1 to about 5% curing additives selected from the group
consisting of aromatic sulfinate salts; [0030] (viii) from about
0.1 to about 5% fluoride-releasing ingredient selected from the
group consisting of cetylamine hydrofluoride (CAF); [0031] (ix)
from about 0.1 to about 10% filler particles selected from the
group consisting of fumed silica and functionalized nano-particles;
[0032] (x) from about 0.05 to about 2% stabilize; [0033] (xi) from
about 1 to about 35% water; and [0034] (xii) from about 5 to about
60% water-miscible polar organic solvent selected from the group
consisting of acetone or alcohol.
[0035] According to the present invention, there is provided both
Two-component and One-component Self-Etching Adhesive (2P-SEA, and
1P-SEA). The new self-etching adhesive materials achieve good
adhesion performance with a simple one-coat application, without
the need of tooth etching using phosphoric acid tooth gel in its
specific indications.
[0036] 2P-SEA is a LC/SC Dual Cure Self-Etching Adhesive system
that is applied onto tooth cavity surfaces with premixed Solutions
A and B prior to bonding the direct light cure composite
restorations or indirect cemented restorations. The preferred
2P-SEA composition contains optimized mixture of polymerizable
acidic monomers with phosphoric acid and/or carboxylic acid groups,
various hydrophilic and hydrophobic meth(acrylates) monomers,
structure resin monomer, crosslinker, curing agent (L-TPO plus
CQ/EDAB (or CQ/DMABN) and cure-promoting additives (NaTs),
stabilizer, water and other solvents (such as Acetone, or other
alcohols (methanol, ethanol, t-butanol)). Unlike previous
self-etching adhesives, the 2P-SEA solution according to the
invention can be used to bond both Visible Light Cured (VLC)
composite type restorations and cemented indirect restorations
(prefabricated metal/porcelain/composite
Inlays/Onlays/Veneers/Crowns/Bridges) to human teeth substrate
(enamel and dentine) without the need of separate acid-etching or
priming pre-treatment teeth bonding step. The 2P-SEA application
procedure remains the same, i.e. [Part A/B Mix ratio=2/1 by w/w/ or
v/v, 1Coat/20 seconds wet, air dry, LC 10'' or 20''], whether it is
for direct or indirect bonding restorations. The 2P-SEA also showed
improved bonding performance over prior art products, with enamel
bond strength of at least greater than 20 MPa and dentin bond
strength of at least greater than 15-20 MPa. The bonding
performance sustained even after excessive thermal stressing
(1800.times. or 5000.times., 55/5-.degree. C. thermal cycling) or
up to 12 week/50.degree. C. thermal aging, indicating good bonding
durability and materials shelf-life stability. In comparison with
current commercial Self-Etching Adhesive products, 2P-SEA also
shows better or equivalent bonding performance, with more
versatility in applications.
[0037] 1P-SEA according to the inventions is a Single Step Light
Cured Self-Etching Adhesive that is contained in one single package
(bottle or single unit-dose) prior to applying onto tooth cavity
surfaces to bond the direct light cure composite type restorations.
The preferred 1P-SEA composition contains optimized mixture of
polymerizable acidic monomers with phosphoric acid and/or
carboxylic acid groups, various hydrophilic and hydrophobic
meth(acrylates) monomers, structure resin monomer, crosslinker,
curing agent (L-TPO and/or CQ/DMABN; (or CQ/EDAB), stabilizer,
water and other solvents (acetone, or alcohol). Unlike previous
self-etching adhesives, one-component SEA materials shows high
initial bonding strength and good bonding durability and long-term
bonding performance as well, with enamel bond strength of at least
greater than 20 MPa and dentin bond strength of at least greater
than 15-20 MPa. The new 1P-SEA materials achieve good adhesion
performance with a simple "one-coat" application technique, without
separate acid-etching or tooth-priming step. The bonding
performance of 1P-SEA sustains even after excessive thermal
stressing (1800.times. or 5000.times., 55/5-.degree. C. thermal
cycling) or 4 week/50.degree. C. thermal aging, indicating good
bonding durability and materials shelf-life stability. In
comparison with current commercial Self-Etching Adhesive products,
1P-SEA shows better or equivalent bonding performance, with better
storage stability and longer shelf life. The 1P-SEA shows improved
bonding performance over prior art products, with high initial and
sustained long-term bonding performance [enamel bond strength of at
least greater than 20 MPa and dentin bond strength of at least
greater than 15-20 MPa] and good bonding durability. Unlike prior
art self-etching adhesive products in which the active ingredients
of the composition have to be divided into two or more parts in
different packages to avoid composition degradation or
polymerization, the 1P-SEA overcome the one-package storage
stability issue by choosing the optimum ingredients of appropriate
acidic strength acidic monomers, effective and stable VLC
photoinitiator in acidic aqueous solution, A bifunctional
hydrophilic monomer with higher crosslinking and less tendency to
hydrolysis, and minimum amount of water incorporated into a
water-miscible polar aprotic organic solvent. Optionally, micro- or
nanosized fillers and fluoride-releasing agent can also be added to
enhance the product performance and provide fluoride release
feature. When used with a separate Self-Cure Activator component,
the 1P-SEA application can be expanded to bond cemented indirect
restorations (prefabricated metal/porcelain/composite
Inlays/Onlays/Veneers/Crowns/Bridges) with human teeth substrate
(enamel and dentine) without separate acid-etching or priming
pre-treatment step.
[0038] Both 2P-SEA, and 1P-SEA materials can achieve good adhesion
performance with a simple one-coat application, without the need of
using phosphoric acid tooth gel in its specific indications as
follows.
[0039] For Two-component Dual Cure Self-Etching Adhesive (2P-SEA),
it is indicated to bond both Visible Light Cure (VLC)
composite/compomer direct restorations and cemented indirect
restorations (prefabricated metal/porcelain/composite
Inlays/Onlays/Veneers/Crowns/Bridges) to human teeth substrate
(enamel and dentine) without the need of separate acid-etching or
priming pre-treatment teeth bonding step. Whether it is used for
direct or indirect bonding restorations, the 2P-SEA application
procedure remains the same, i.e. [Part A/B Mix ratio=2/1 by w/w/ or
v/v, 1Coat/20 seconds wet, air dry, LC 10 or 20 seconds]. In
addition, the 2P-SEA can also be used for adhesive repairs of tooth
restorations (composite/porcelain/amalgam). It can also be used as
a cavity varnish or desensitizer.
[0040] For One-component Visible Light Cure Self-Etching Adhesive
(1P-SEA), it is indicated to bond VLC composite/compomer direct
restorations to human teeth substrate (enamel and dentine) without
the need of separate acid-etching or priming pre-treatment teeth
bonding step. When used with a separate Self-Cure Activator
component, the 1P-SEA can also bond for cemented indirect
restorations (prefabricated metal/porcelain/composite
Inlays/Onlays/Veneers/Crowns/Bridges) to human teeth substrate
(enamel and dentine) without separate acid-etching or priming
pre-treatment step. In addition, 1P-SEA can also be used as a
cavity varnish or desensitizer.
[0041] Both Two-component and One-component Self-Etching Adhesive
(2P-SEA, and 1P-SEA) prototypes developed represent an improvement
to the existing commercial self-etching adhesive products. The new
self-etching adhesive materials achieve good adhesion performance
with a simple one-coat application, without the need of separate
acid-etching or priming pre-treatment teeth bonding step.
[0042] The property improvement results from the unique composition
of 2P-SEA which comprises of an optimized mixture of acidic
adhesion promoters with phosphoric acid and/or carboxylic acid
functional groups (e.g. PENTA and OEMA), various hydrophilic and
hydrophobic meth(acrylates) monomers, curing agent (L-TPO plus
CQ/EDAB (or CQ/DMABN or other photo-coinitiator) and cure-promoting
additives sulfinate salts, NaTs), water and volatile polar solvents
(acetone, or alcohol). Unlike previous commercialized
multi-component self-etching adhesives, the 2P-SEA Dual Cure can be
used to bond both direct VLC composite type restorations and
cemented indirect restorations (prefabricated
metal/porcelain/composite Inlays/Onlays/Veneers/Crowns/Bridges) to
human teeth substrate (enamel and dentine) without the need of
separate acid-etching or priming pre-treatment teeth bonding step.
The application procedure of 2P-SEA remains the same, i.e. [Part
A/B Mix ratio=2/1 by w/w/ or v/v, 1Coat/20 seconds wet, air dry,
LC], whether it is for direct or indirect bonding restorations. The
2P-SEA also showed improved bonding performance over prior art
products, with enamel bond strength of at least greater than 20 MPa
and dentin bond strength of at least greater than 18 (15-20) MPa.
The bonding performance sustained even after excessive thermal
stressing (1800.times. or 5000.times., 55/5-.degree. C. thermal
cycling) or up to 12 week/50.degree. C. thermal aging, indicating
good bonding durability and materials shelf-life stability. In
comparison with current commercial Self-Etching Adhesive products,
2P-SEA also shows better or equivalent bonding performance, with
more versatility in applications (see attached Comparison to
Competitions).
[0043] A first Two-component LC/SC Dual Cure SEA has the following
characteristics: [0044] Bond both direct and indirect with same
simple application technique; [0045] Simple system (2 bottle or
single unit dose packaged, no rinse/no "dry & wet issues, no
more sensitivity); [0046] Easy to use (one coat/1-step application
technique); [0047] High Bonding Performance and Durable (stable);
[0048] Versatility (2 bottle adhesive system for both direct and
Indirect restoration bonding applications); and, [0049] 2+ year
shelf life (no refrigeration needed).
[0050] 1P-SEA is a Light Cured Self-Etching Adhesive contained in
one single package (bottle or single unit-dose) prior to applying
onto tooth cavity surfaces to bond the direct light cure composite
type restorations. Unlike prior art self-etching adhesive products
of which the active ingredients of the composition have to be
divided into two or more parts in different packages to avoid
composition degradation or polymerization, the 1P-SEA overcome the
one-package storage stability issue by choosing the optimum
ingredients required for good self-etching adhesion performance
without presenting the hydrolysis stability issues commonly seen in
other self-etching adhesives. The improved adhesion property and
feature/benefits offered by 1P-SEA are made possible by optimum
combination of 1P-SEA compositions, preferably comprised of
appropriate acidic strength adhesion monomers (PENTA, 4-META, and
other acidic monomers), effective and stable VLC photoinitiator in
the acidic aqueous solution, a bifunctional hydrophilic monomer
with higher crosslinking and less tendency to hydrolysis, and
minimum amount of water incorporated into a water-miscible polar
aprotic organic solvent. Optionally, micro- or nanosized fillers
and fluoride-releasing agent can also be added to 1P-SEA
composition to enhance the product performance and provide fluoride
release feature. When used with a separate Self-Cure Activator
component, the 1P-SEA application can be expanded to bond cemented
indirect restorations (prefabricated metal/porcelain/composite
Inlays/Onlays/Veneers/Crowns/Bridges) with human teeth substrate
(enamel and dentine) without separate acid-etching or priming
pre-treatment step. The 1P-SEA shows improved bonding performance
over prior art products, with high initial and sustained long-term
bonding performance [enamel bond strength of at least greater than
20 MPa and dentin bond strength of at least greater than 15-20 MPa]
and good bonding durability. The new 1P-SEA materials achieve good
adhesion performance with a simple "one-coat" one-step application
technique, without separate acid-etching or tooth-priming step. The
bonding performance of 1P-SEA sustains even after excessive thermal
stressing (5000.times., 55/5-.degree. C. thermal cycling) or 4
week/50.degree. C. thermal aging, indicating good bonding
durability and materials shelf-life stability. In comparison with
current commercial Self-Etching Adhesive products, 1P-SEA shows
better or equivalent bonding performance, with better storage
stability and longer shelf life (see attached Comparison to
Competitions).
[0051] A TRUE one-component SEA has the following characteristics:
[0052] Simple (1 bottle or single unit dose packaged, no mix/no
rinse/no "dry & wet issues, no more sensitivity); [0053] Fast
and Easy (one coat/1-step within 40''); [0054] High Bonding
Performance and Durable (stable); [0055] 2 year shelf life; [0056]
Fluoride releasing; and, [0057] Versatility (expandable to Indirect
Applications with Self Cure Activator component). General
Experimental
[0058] The compositions according to the present invention
variously contain the following components which are listed with
their appropriate functions. [0059] PENTA: Acidic monomer, adhesion
promoter; [0060] OEMA: Acidic monomer, adhesion promoter; [0061]
(4-META: Acidic monomer, adhesion promoter); [0062] AHPMA:
Difunctional hydrophilic monomer, wetting agent; [0063] HEMA:
Monofunctional hydrophilic monomer, wetting agent; [0064] TEGMA:
Reactive diluent; [0065] UDMA: Structural resin; [0066] TMPTMA:
Crosslinker; [0067] Photoinitiators and stabilizers; [0068] Curing
additives: sulfinate salts NaTs; [0069] Acetone (or alcohol):
Solvent, resin carrier; and, [0070] Water: ionizing medium for
protonic acid, solubilizing medium for calcium salts, essential for
effective enamel etching.
[0071] It is desired to have the following characteristics: [0072]
Minimum amount of water incorporated; [0073] Water miscible polar
aprotic organic solvent, eg. acetone as solvent to minimize
hydrolysis and solvolysis; [0074] L-TPO as VLC photoinitiator:
effective and stable in acidic aqueous solution. L-TPO plus
CQ/DMABN or CQ/EDAB can be cured effectively by both typical dental
halogen QTH or LED curing units; [0075] for 1P-SEA, a bifunctional
hydrophilic monomer included: higher crosslinking, less prone to
hydrolysis and less contributing to a medium favorable for
hydrolysis; and, [0076] for 1P-SEA, appropriate acidic strength of
acidic monomers were identified, that are strong enough to etch
both dentin and enamel, but with adequate hydrolytic stability.
[0077] Several series of LC/SC Dual Cure Two-part SEA with good
bonding performance were identified, with the preferred 2P-SEA
composition and formulations (LCH57-78-2/LCH56-140) listed in the
attachment. the 2P-SEA Dual Cure can be used to bond both direct
VLC composite type restorations AND cemented indirect restorations
to human teeth substrate (enamel and dentine) without the need of
separate acid-etching or priming pre-treatment teeth bonding
step.
[0078] The 2P-SEA also showed improved bonding performance over
prior art products, with enamel bond strength of at least greater
than 20 MPa and dentin bond strength of at least greater than 18
(15-20) MPa. The bonding performance sustained even after excessive
thermal stressing (1800.times. or 5000.times., 55/5-.degree. C.
thermal cycling) or up to 12 week/50.degree. C. thermal aging,
indicating good bonding durability and materials shelf-life
stability.
[0079] Two very promising one-part SEA inventions were identified.
One embodiment of the 1P-SEA invention contains PENTA as acidic
monomer and another has PENTA/4-META as acidic monomers.
[0080] L-TPO as VLC photoinitiator: effective and stable in acidic
aqueous solution. L-TPO plus CQ/DMABN or CQ/EDAB photoinitiator
combination is stable in acid environment, and can be cured
effectively by both typical dental halogen QTH or LED curing
units.
[0081] They exhibited excellent baseline bond strength on both
dentin and enamel. On storage 50.degree. C./3 weeks, they still had
acceptable bond strength to both dentin and enamel (dentin SBS
greater than 15 MPa and enamel SBS greater than 20 MPa).
[0082] The BS samples applied with the new SEA invention were
thermocycled 55-5.degree. C. for 1800 cycles or 5000.times.. No
significant change in both dentin and enamel bond strength was
observed.
Samples Preparation and Testing for Measuring Shear Bond Strength
of Composite Restoratives or Cemented Indirect Restorations
(Inlays/Onlays/Crowns/Bridges) to Human Tooth Substrates (Dentin or
Enamel) Using SEA (2P-SEA or 1P-SEA)
[0083] The extracted human molars were immersed in water and stored
in a 4.degree. C. refrigerator prior to use. Dentin or enamel was
sanded using wet 320 grit abrasive paper and then 600 grit. A
dental adhesive was applied to dentin or enamel surface and
scrubbed with a microbrush for 20 seconds. The surface was blown
dry 10 seconds with air stream and light cured 10 seconds using
Spectrum 800 at 550 mw/cm.sup.2. Gelatin capsules (#5) were
half-filled with TPH composite and cured in a VL curing oven. The
capsules were filled with TPH and positioned onto the coated
dentin. The flash was gently removed using a dental explorer and
the composite was light cured 3.times.20'' sequentially around the
circumference of the cylinder with Spectrum 800 at 550
mw/cm.sup.2.
[0084] For indirect cementation bond strength, The capsules or
plastic matrix were filled with mixed composite resin cements (e.g.
Calibra resin cement by Dentsply) and positioned onto the coated
dentin or enamel surface. The flash was gently removed using a
dental explorer and the restorative post was light cured
3.times.20'' sequentially around the circumference of the cylinder
with Spectrum 800 at 550 mw/cm.sup.2, or leaves self-cure for resin
cement.
[0085] The samples were embedded in tray resin and the posts were
ensured to be perpendicular to the bonding surface. The shear bond
strength was obtained in compressive shear mode with a Instron at a
crosshead speed of 5 mm/min). The similar procedure was followed to
test enamel shear bond strength except that plastic straws with
smaller diameter were used instead of gelatin capsules.
EXAMPLES
2P-SEA Example 1
[0086] A 2P-SEA comprises of liquid A and Liquid B. The liquid A is
comprised of 20.0 parts by weight of dipentaerythritol
pentaacrylate phosphoric acid ester (PENTA), 15.0 parts by weight
of OEMA resin, 5 parts by weight of hydroxylethyl methacrylate
(HEMA), 10.0 parts by weight of triethyleneglycoldimethacrylate
(TEGDMA), 5.0 parts by weight of 1,6-Bis
(methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexane (UDMA),
2.0 parts by weight of trimethylolpropane trimethacrylate (TMPTMA),
2.0 parts by weight of diphenyl(2,4,6-trimethylbenzoyl)phosphine
oxide (L-TPO), 0.30 parts by weight of camphouquinone (CQ), and 1.0
parts of EDAB (or 1.0 parts of the 4-dimethylaminobenzonitrile
(DMABN), 0.40 part by weight of butylated hydroxytoluene (BHT),
44.3 parts by weight of solvent acetone (or ethanol, or
2-methyl-2-propanol, or methanol,). The liquid B is comprised of
2.0 parts by weight of sodium aromatic sulfinate (NaTs), 19.9 parts
by weight of ethanol, and 78.1 parts by weight of deionized water.
The 24 hour composite to dentin and enamel bond strength was
measured 17.9 (1.6) MPa and 30.0 (5.6) MPa, respectively, without
separate etching step. The 24 hour composite resin cement (Calibra)
to dentin and enamel bond strength was measured as 19.6 (5.8) MPa
and 23.3 (6.6) MPa, respectively, without separate etching step.
The thermal cycled (1800 cycle, between 55/5.degree. C.) composite
to dentin and enamel bond strength was measured 16.5 (2.8) MPa and
35.6 (3.3) MPa, respectively, without separate etching step.
2P-SEA Example 2
LCH68-119-2 & LCH68-120-2
[0087] A 2P-SEA comprises of Liquid A and Liquid B. The Liquid A is
comprised of 35.0 parts by weight of dipentaerythritol
pentaacrylate phosphoric acid ester (PENTA), 10.0 parts by weight
of OEMA resin, 10.0 parts by weight of
triethyleneglycoldimethacrylate (TEGDMA), 10.0 parts by weight of
1,6-Bis (methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexane
(UDMA), 2.0 parts by weight of trimethylolpropane trimethacrylate
(TMPTMA), 2.0 parts by weight of
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (L-TPO), 0.30 parts
by weight of camphouquinone (CQ), and 1.0 parts of EDAB, 0.40 part
by weight of butylated hydroxytoluene (BHT), 29.3 parts by weight
of 2-methyl-2-propanol. The liquid B is comprised of 2.0 parts by
weight of sodium aromatic sulfinate (NaTs), 49.9 parts by weight of
ethanol, and 48.1 parts by weight of deionized water. The 24 hour
composite to dentin and enamel bond strength was measured as 19.5
(1.3) MPa and 25.3 (4.7) MPa, respectively, without separate
etching step. The 24 hour composite resin cement (Calibra) to
dentin and enamel bond strength was measured as 15.5 (1.7) MPa and
27.2 (2.0) MPa, respectively, without separate etching step.
Direct and Indirect Adhesion of Long-term (18 months) Room
Temperature Aged 2P-SEA Materials
[0088] The adhesion SBS study for 1.5 year (18 months) room ambient
temperature aged above 2P-SEA Dual Cure adhesive materials
(Lot#33801 & Lot#33201) showed direct composite enamel SBS of
27.0 MPa (100% cohesive failure) and dentin SBS of 18.0 MPa (100%
cohesive failure), while a Indirect cementation enamel SBS of 24.5
MPa (100% cohesive failure) and dentin SBS of 14.4 MPa (60%
cohesive failure) were also obtained for the same 2P-SEA materials
using the same technique for both direct and indirect applications.
Those results demonstrated that the 2P-SEA material has very good
stability and adhesion results, with at least 1.5-year (18 months)
shelf life at room temperature so far.
2P-SEA Example 3
[0089] A 2P-SEA comprises of Liquid A and Liquid B. The Liquid A is
comprised of 20.0 parts by weight of dipentaerythritol
pentaacrylate phosphoric acid ester (PENTA), 15.0 parts by weight
of OEMA resin, 10.0 parts by weight of
triethyleneglycoldimethacrylate (TEGDMA), 5.0 parts by weight of
1,6-Bis(methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexa- ne
(UDMA), 2.0 parts by weight of trimethylolpropane trimethacrylate
(TMPTMA), 2.0 parts by weight of
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (L-TPO), 0.30 parts
by weight of camphouquinone (CQ), and 1.0 parts of EDAB, 0.40 part
by weight of butylated hydroxytoluene (BHT), 0.2% cetylamine
hydrofluoride (CAF) and 1% silanated fumed silica (Aerosil 380),
42.0 parts by weight of 2-methyl-2-propanol (or ethanol or
Acetone). The liquid B is comprised of 2.0 parts by weight of
sodium aromatic sulfinate (NaTs), 19.9 parts by weight of ethanol,
and 78.1 parts by weight of deionized water. The 24 hour composite
to dentin and enamel bond strength was measured as 21.8 (2.2)) MPa
and 25.0 (3.1) MPa, respectively, without separate etching step.
The 24 hour composite resin cement (Calibra) to dentin and enamel
bond strength was measured as 13.1 (2.5) MPa and 22.6 (3.9) MPa,
respectively, without separate etching step.
2P-SEA Example 4
Aqueous SCA LCH68-120-2
[0090] An aqueous Self Cure Activator (SCA) as 2P-SEA Liquid B was
prepared according to the following procedures. The liquid B is
comprised of 2.0 parts by weight of sodium aromatic sulfinate
(NaTs), 49.9 parts by weight of ethanol, and 48.1 parts by weight
of deionized water. The above 2P-SEA Liquid B can be used with any
2P-SEA Liquid A as described or used with other one-component
dental adhesives in the intended direct composite or indirect
cementation bonding applications.
1P-SEA Example 1
[0091] A mixture comprising 3.3 parts by weight of
4-methacryloxyethyltrimellitic anhydride (4-META), 13.3 parts by
weight of dipentaerythritol pentaacrylate phosphoric acid ester
(PENTA), 6.7 parts by weight of 3-(acryloyloxy)-2-hydroxypropyl
methacrylate (AHPMA), 3.3 parts by weight of
triethyleneglycoldimethacrylate (TEGMA), 10.9 parts by weight of
1,6-Bis(methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexane
(UDMA), 1.7 parts by weight of trimethylolpropane trimethacrylate
(TMPTMA), 1.7 parts by weight of
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.13 part by
weight of butylated hydroxytoluene, 42.3 parts by weight of acetone
and 16.7 parts by weight of deionized water were prepared. The
dentin and enamel bond strength was measured 22.4 MPa and 33.8 MPa,
respectively. The thermal cycled (1800 cycle, between 55/5.degree.
C.) composite to dentin and enamel bond strength was measured 25.5
MPa and 25.9 MPa, respectively, without separate etching step. The
more excessive 5000.times. thermal cycled composite to dentin and
enamel bond strength was measured as 25.0 MPa and 28.3 MPa,
respectively, without separate etching step. The sustained thermal
cycled enamel and dentin bond strength indicated the good bond
durability and potential good long-term bonding performance in a
clinical setting.
1P-SEA Example 2
[0092] A mixture comprising 25.0 parts by weight of
dipentaerythritol pentaacrylate phosphoric acid ester (PENTA), 7.9
parts by weight of 3-(acryloyloxy)-2-hydroxypropyl methacrylate
(AHPMA), 5.5 parts by weight of 2-hydroxyethyl methacrylate (HEMA),
10.9 parts by weight of
1,6-Bis(methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexane
(UDMA), 1.7 parts by weight of trimethylolpropane trimethacrylate
(TMPTMA), 1.7 parts by weight of
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.13 part by
weight of butylated hydroxytoluene, 42.3 parts by weight of acetone
and 16.7 parts by weight of deionized water were prepared. The
dentin and enamel bond strength was measured 21.4 MPa and 26.3 MPa,
respectively. The thermal cycled (1800 cycle, between 55/5.degree.
C.) composite to dentin and enamel bond strength was measured 21.1
MPa and 28.3 MPa, respectively, without separate etching step.
1P-SEA Example 3
[0093] 50.degree. C. Accelerated Storage Stability Test of Two
Representative Formulations TABLE-US-00002 TABLE 1 SEA formulations
and bond strength Formulation HL2-5 HL2-7 Component % wt % wt PENTA
25.0 20.0 4-META 0 3.3 AHPMA 7.9 0 HEMA 0 3.3 UDMA 3.5 9.9 TMPTMA
1.7 1.7 L-TPO 1.7 1.7 BHT 0.13 0.13 Acetone 41.7 43.3 Water 18.3
16.7 SUM 100 100 Dentin SBS 0 week 50.degree. C. 21.4 (3.9) 22.4
(5.2) (MPa): 2 week 50.degree. C. 17.8 (5.8) 14.2 (4.2) mean (SD) 3
week 50.degree. C. 17.6 (6.4) 21.8 (0.7) 4 week 50.degree. C. 8.2
(2.2) 14.8 (2.1) Enamel SBS 0 week 50.degree. C. 26.3 (4.6) 33.8
(3.1) (MPa): 2 week 50.degree. C. 30.6 (11.1) 19.7 (3.1) mean (SD)
3 week 50.degree. C. 29.4 (12.0) 24.2 (9.0) 4 week 50.degree. C.
14.4 (4.1) 12.8 (7.8)
1P-SEA Example 4
50.degree. C. Accelerated Storage Stability Test on Formulations
with PENTA/BMAP
[0094] Formulation HL1-72-4 consisted of 3.3 wt % BMAP, 20 wt %
AHPMA, 3.8 wt % HEMA, 3.8 wt % TEGDMA, 10.8 wt % UDMA, 1.7 wt %
TMPTMA, 4.2 wt % PENTA, 1.7 wt % L-TPO, 0.27 wt % CQ, 0.33 wt %
BHT, 33.3 wt % acetone and 16.7 wt % water.
[0095] Formulation HL1-72-5 consisted of 6.7 wt % BMAP, 16.7 wt %
AHPMA, 3.8 wt % HEMA, 3.8 wt % TEGDMA, 10.8 wt % UDMA, 1.7 wt %
TMPTMA, 4.2 wt % PENTA, 1.7 wt % L-TPO, 0.27 wt % CQ, 0.33 wt %
BHT, 33.3 wt % acetone and 16.7 wt % water.
[0096] The accelerated storage stability test on two PENTA/BMAP
based formulations was conducted. The samples HL1-72-4 and HL1-72-5
in black plastic bottles were placed in a 50.degree. C. oven for
three weeks. The appearance and pH were checked after one, two and
three weeks; The solutions remain clear, colorless and homogeneous.
pH did not seem to change. Both samples had good cure under
irradiation of Spectrum 800 at 550 mw/cm.sup.2 for 20''. After one
week, the dentin bond strength of HL1-72-4 was reduced to 9.7 (2.9)
MPa; after two weeks it was 5.6 (3.5) MPa. After three weeks, the
dentin shear bond strength of HL1-72-4 and HL1-72-5 was 5.7 (1.3)
MPa and 2.3 (2.4) MPa, respectively; the enamel shear bond strength
of HL1-72-4 was 2.2 (1.0) while posts fell off during storage for
HL1-72-5 enamel SBS test. Even when enamel was etched with Caulk
34% Tooth Conditioner Gel, the bond strength of HL1-72-4 stored at
50.degree. C. for three weeks was only 4.8(0.7) MPa. This suggests
that a disastrous hydrolysis of resins in the formulation has
occurred and the reduced mechanical strength of cured resins leads
to the lowered bond strength. TABLE-US-00003 TABLE 2 50.degree. C.
Accelerated Storage Stability Test on PENTA/BMAP based
one-component aqueous formulations Shear Bond Sample Strength 0
week 1 week 2 week 3 week I.D. (MPa) 50.degree. C. 50.degree. C.
50.degree. C. 50.degree. C. HL1-72-4 Dentin 10.9 (4.7) 9.7 (2.9)
5.6 (3.5) 5.7 (1.3) Enamel 33.4 (2.0) 2.2 (1.0) HL1-72-5 Dentin
10.9 (6.3) 2.3 (2.4) Enamel 27.4 (4.7) Posts fell off
1P-SEA Example 5
[0097] TABLE-US-00004 TABLE 3 SEA formulation HL1-126-1
(PENTA/GDMAM as acidic monomers, acetone/water as solvent)
Formulation HL1-126-1 Component % wt Glycerol dimethacrylate/ 3.3
maleate (GDMAM) AHPMA 13.3 HEMA 10.5 TEGDMA 3.9 UDMA 11.3 TMPTMA
1.7 PENTA 4.2 L-TPO 1.7 BHT 0.13 Acetone 33.3 Water 16.7 SUM 100
Dentin SBS 0 week, 50.degree. C. 19.4 (3.1) (MPa) 2 week,
50.degree. C. 13.1 (4.2) Enamel SBS 0 week, 50.degree. C. 24.9
(13.4) (MPa) 2 week, 50.degree. C. 16.8 (5.4)
1P-SEA Example 6
[0098] TABLE-US-00005 TABLE 4 Formulations with EGMP as acidic
monomer and water/ethanol as solvent Formulation HL1-25 HL1-27
HL1-28 HL1-30 HL1-33 HL1-39 Component % wt % wt % wt % wt % wt % wt
EGMP 20 20 20 20 20 12 BMAP 0 0 0 0 0 8 HEMA 10 14.6 12.6 16.6 10
12.6 AHPMA 0 0 0 0 7.6 0 TEGDMA 10 10 10 10 10 10 UDMA 5 5 10 10 5
5 TMPTMA 2 2 2 2 2 2 PENTA 0 5 0 0 0 5 L-TPO 2 2 4 0 4 5 CQ 0.2 0.2
0.2 0.2 0.2 0 EDAB 0.8 0.8 0.8 0.8 0.8 0 BHT 0.4 0.4 0.4 0.4 0.4
0.4 Ethanol 20 20 20 20 20 20 Water 30 20 20 20 20 20 SUM 100 100
100 100 100 100 Dentin SBS (MPa) 4.9 (2.1) 4.2 (1.1) 6.3 (1.4) No
cure 5.0 (1.0) 5.0 (1.6)
[0099] TABLE-US-00006 TABLE 5 Formulations with EGMP as acidic
monomer and water/acetone as solvent Formulation HL1-38 HL1-47
Component % wt % wt EGMP 20 25 HEMA 12.6 15.8 TEGDMA 10 15.9 UDMA 5
6.3 TMPTMA 2 2.5 PENTA 5 6.3 L-TPO 5 2.5 CQ 0 0.4 BHT 0.4 0.5
Acetone 20 25 Water 20 0 SUM 100 100 Dentin SBS (MPa) 5.6 (1.7) 4.9
(0.8)
1P-SEA Example 7
[0100] 0.3% cetylamine hydrofluoride (CAF) and 2% Aerosil R974 were
added to HL1-203 and HL2-40 for filled and fluoride-releasing
one-part SEA. The dentin and enamel SBS of the baseline and
50.degree. C. aged samples are summarized in Table 6. Like the base
formulations, 3-week 50.degree. C. aged HL2-87-1 and HL2-87-2 both
still had good bond strength on dentin and enamel. It is noteworthy
that 4-week 50.degree. C. aged HL2-87-1 and HL2-87-2 had dentin SBS
18.7 MPa and enamel SBS16.7 MPa, respectively, significantly higher
than their corresponding base formulations. Their enamel bond
strength, however, was not so different from their base
formulations. TABLE-US-00007 TABLE 6 Bond strength and storage
stability of one-part SEA filled with CAF and Aerosil R974 Sample
I.D. HL2-87-1 HL2-87-2 HL2-40 + HL1-203 + 0.3% CAF + 2% 0.3% CAF +
2% Sample composition Aerosil 974 Aerosil 974 Human Dentin RT
stored 19.8 (5.5) 13.6 (5.7) SBS (MPa): 3 week 50.degree. C. 22.0
(3.5) 21.8 (4.7) Mean (SD) 4 week 50.degree. C. 18.7 (5.1) 16.7
(9.4) RT stored 29.2 (5.1) 27.8 (15.4) 3 week 50.degree. C. 21.0
(6.3) 21.0 (11.2) 4 week 50.degree. C. 10.2 (6.4) 9.4 (3.2)
1P-SEA Example 8
[0101] 0.3% CAF and 2% Dentsply proprietary nanofiller were added
to HL1-203 and HL2-40 for filled and fluoride-releasing one-part
SEA. Bond strength and 50.degree. C. storage stability are
summarized in Table 7. It seems that HL1-230 is not very compatible
with Nanofiller. Somehow, HL2-107-1, the filled version of HL1-203
did not show good enamel bond strength. HL2-107-2, the filled
version of HL2-40, had good dentin and enamel bond strength for the
samples stored at 50.degree. C. up to three weeks, 16.6 MPa on
dentin and 24.7 MPa on enamel. More interestingly, after storage at
50.degree. C. for 4 weeks, its dentin and enamel SBS are 16.8 MPa
and 18.3 MPa, respectively, significantly higher than its
non-filled counterpart. TABLE-US-00008 TABLE 7 Bond strength of
one-part SEA filled with CAF and nanofiller Sample I.D. HL2-107-
HL2-107-2 HL1-203 + HL2-40 + 0.3% CAF + 2% 0.3% CAF + 2% Sample
composition Nanofiller Nanofiller Human Dentin RT stored 17.2 (4.4)
24.5 (4.5) SBS (MPa): 3 week 50.degree. C. 17.3 (7.9) 16.6 (4.5)
Mean (SD) 4 week 50.degree. C. 16.8 (8.5) Human RT stored 14.1
(0.4) 35.7 (6.0) Enamel SBS 3 week 50.degree. C. 16.6 (8.3) 24.7
(4.7) (MPa): Mean 4 week 50.degree. C. 18.3 (5.6) (SD)
1P-SEA Example 9
[0102] A mixture comprising 20.0 parts by weight of
dipentaerythritol pentaacrylate phosphoric acid ester (PENTA), 6.9
parts by weight of 3-(acryloyloxy)-2-hydroxypropyl methacrylate
(AHPMA), 5.0 parts by weight of 2-hydroxyethyl methacrylate (HEMA),
8.0 parts by weight of
1,6-Bis(methacryloyloxyethoxycarbonylamino)-2,4,4-trimethylhexane
(UDMA), 2.0 parts by weight of trimethylolpropane trimethacrylate
(TMPTMA), 1.7 parts by weight of
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.30 parts by
weight of camphouquinone (CQ), and 1.0 parts of
4-dimethylaminobenzonitrile (DMABN) or 1.0 parts of EDAB, 0.2 part
by weight of butylated hydroxytoluene, 0.2 parts of cetylamine
hydrofluoride (CAF), 41.0 parts by weight of acetone and 13.7 parts
by weight of deionized water were prepared. The composite to dentin
and enamel bond strength was measured as 22.5 MPa and 25.3 MPa,
respectively. When the 1P-SEA was used with Self Cure Activator
component, the 24 hour composite resin cement (Calibra) to dentin
and enamel bond strength was measured as 16.0 MPa and 22.0 MPa,
respectively, without separate etching step.
1P-SEA Example 10
[0103] As described in the previous patent examples, 1P-SEA
formulations can use initiators combination of L-TPO and CQ with
different coinitiators (different amines, such as DMABN, EDAB, or
DHEPT) to make the 1P-SEA compatible with both dental halogen QTH
or LED curing lights. Table 8 compares bond strength of three
different experimental 1P-SEA differing only in aromatic amines.
DHEPT and EDAB are two most commonly used co-initiators for CQ. The
formulations containing either DHEPT or EDAB did not lead to
acceptable balanced properties. Only the formulation incorporating
DMABN exhibits the superior balance of bond strength, storage
stability and compatibility with different curing lights (dental
QTH and LED curing lights). DMABN is the first time ever used in
any commercial dental adhesive. TABLE-US-00009 TABLE 8 24 hr Shear
Bond Strength of 1P-SEA Containing Different Co-initiators 1P-SEA
containing 1P-SEA containing 1P-SEA Sample I.D. DMABN DHEPT
containing EDAB Human Dentin RT stored QTH Light 23.2 (3.9) NT 17.0
(7.5) SBS (MPa): Mean LED light 22.0 (4.0) NT 15.6 (5.7) (SD)
50.degree. C. 3 weeks QTH Light 15.3 (4.2) NT 14.5 (6.9) LED light
15.8 (6.1) NT 16.8 (6.8) Human Enamel RT stored QTH Light 26.4
(5.3) 13.5 (6.7) 32.7 (7.2) SBS (MPa): Mean LED light 32.0 (3.0) NT
30.1 (7.3) (SD) 50.degree. C. 3 weeks QTH Light 26.7 (5.3) NT 7.6
(2.0) LED light 35.3 (7.9) NT 24.8 (13.3)
* * * * *